More precisely, the present invention has as its object the implementation of a sail suitable for the operation of a commercial or passenger transport vessel, i.e. a sail capable of being used intensively (even on vessels the righting moment whereof is very high), regardless of the meteorological conditions encountered, while maximizing the return on investment of the rig and the sail. One of the difficulties with existing sails, when they are used in large vessels, relates to the high forces developed by these sails, which can exceed 100 tonnes in the most heavily loaded zones such as the clews. These values are considerably greater than those which sails manufactured based on currently available technologies are able to resist (on the order of 50 tonnes).
At present, the sails available on the market are, to the knowledge of the present applicant, thin membranes of three types. The first consists of sails made of fabrics in sewn and/or glued widths. This method is very costly and reaches a natural limit for the manufacture of sails of large dimensions due to the inherent weight of the fabrics to be handled and the capacity of the machines for sewing and piercing considerable thicknesses of very strong fabric.
Also known are sails made of fabric panels, panels assembled together mechanically using circular carbon battens (method developed by the Doyle Sails company) and by a cable which runs along the leach of the sail (the free side of the triangle formed by the edges of the sail, i.e. the side which is not intended to be attached to the mast or to the boom). Finally, sails made by molding are known, formed by assembling high-strength fibers using a flexible resin or film, using a mold (3Di and 3DL methods of the North Sails company, for example). This method is very costly and essentially intended for competition and for the “super yacht” field, i.e. for luxury yachts. Methods intermediate to the aforementioned exist, particularly when the dimension of the sails is greater than that of the molds and the sails are implemented based on two or three molded subassemblies assembled together by sewing and/or gluing. One technique of this type is employed for example by the Incidence Sails sail loft.
These existing sails have, however, the disadvantages mentioned above in their lack of resistance to large forces when their surface increases substantially, so that there does not exist, to the knowledge of the present applicant, sails of large dimensions capable of resisting forces on the order of 100 tonnes. Even the device described in document WO 2010/094770, in the name of the present applicant, does not completely solve this set of problems. The present invention has the aim of filling this gap and proposing a sail which is resistant to large forces and the use whereof remains substantially identical to current sails.